Photo-Electro Active Nanocomposite Silk Hydrogel for Spatiotemporal Controlled Release of Chemotherapeutics: An In Vivo Approach Towards Suppressing Solid Tumor Growth.

Conventional systemic chemotherapeutic regimens suffer from challenges such as non-specificity, shorter half-life, clearance of drugs and dose-limiting toxicity. Localized delivery of chemotherapeutic drugs through non-invasive spatiotemporally controllable stimuli-responsive drug delivery systems could overcome these drawbacks while utilizing drugs approved for cancer treatment. In this regard, we developed photo-electro active nanocomposite silk-based drug delivery systems (DDS) exhibiting, on-demand drug release in vivo. A functionally modified single-walled carbon nanotube loaded with doxorubicin was embedded within cross-linker free silk hydrogel. The resultant nanocomposite silk hydrogel showed electrical field responsiveness and near-infrared (NIR) laser-induced hyperthermal effect. The remote application of these stimuli in tandem or independent manner led to the increased thermal and electrical conductivity of nanocomposite hydrogel, which effectively triggered the intermittent on-demand drug release. In a proof-of-concept in vivo tumor regression study, the nanocomposite hydrogel was administered in a minimally invasive way at the periphery of the tumor by covering most of it. During the 21-day study, drastic tumor regression was recorded upon regular stimulation of nanocomposite hydrogel with simultaneous or individual external application of an electric field and NIR laser. Tumor cell death marker expression analysis uncovered the induction of apoptosis in tumor cells leading to its shrinkage. Heart ultrasound and histology revealed no cardiotoxicity associated with localized DOX treatment. To our knowledge, this is also the first report to show the simultaneous application of electric field and NIR laser in vivo for localized tumor therapy, and our results suggested that such strategy might have high clinical translational potential.